Method and unit for controlling a clutch powered by a hydraulic actuator

Abstract

A method and unit for controlling a clutch powered by a hydraulic actuator having a work chamber connected to a solenoid valve; a target value of the pressure of the fluid inside the work chamber is generated, an actual value of the pressure of the fluid inside the work chamber is measured, and a control signal for controlling the solenoid valve is calculated using feedback control of the pressure of the fluid inside the work chamber; and the target value of the pressure of the fluid is generated on the basis of an actual value of the position of the hydraulic actuator, and of a target value of the position of the hydraulic actuator.

1. A method of controlling a clutch ( 7 ) powered by a hydraulic actuator ( 15 ) comprising a work chamber ( 28 ), which is filled with a fluid and connected to a solenoid valve ( 25 ) for selective connection to a drain tank ( 19 ) for draining the fluid, or to a storage tank ( 23 ) for accumulating pressurized fluid; the method providing for generating a target value (Pos*) of the position of the hydraulic actuator ( 15 ), measuring an actual value (Pos) of the position of the hydraulic actuator ( 15 ), and calculating a control signal (I*) for controlling the solenoid valve ( 25 ) by feedback control of the position of the hydraulic actuator ( 15 ); and the method being characterized by generating a target value (Put*) of the pressure of the fluid inside the work chamber ( 28 ), estimating an actual value (Put) of the pressure of the fluid inside the work chamber ( 28 ), and calculating the control signal (I*) using both feedback control of the position of the hydraulic actuator ( 15 ), and feedback control of the pressure of the fluid inside the work chamber ( 28 ). 
   
   
     2. A method as claimed in  claim 1 , wherein the actual value (Put) of the pressure of the fluid inside the work chamber ( 28 ) is estimated by a pressure measurement inside the work chamber ( 28 ). 
   
   
     3. A method as claimed in  claim 1 , wherein the actual value (Put) of the pressure of the fluid inside the work chamber ( 28 ) is estimated by a pressure measurement inside a pipe ( 27 ) extending between the work chamber ( 28 ) and the solenoid valve ( 25 ) and connected permanently to the work chamber ( 28 ). 
   
   
     4. A method as claimed in  claim 3 , wherein the pressure measurement is made by a sensor ( 35 ) located inside the pipe ( 27 ) and close to the work chamber ( 28 ). 
   
   
     5. A method as claimed in  claim 1 , wherein the target value (Put*) of the pressure of the fluid inside the work chamber ( 28 ) is generated as a function of the actual value (Pos) of the position of the hydraulic actuator ( 15 ), and of the target value (Pos*) of the position of the hydraulic actuator ( 15 ). 
   
   
     6. A method as claimed in  claim 5 , wherein a forecast value (P 1 ) predicting the value of the pressure of the fluid inside the work chamber ( 28 ) is calculated; the target value (Put*) of the pressure of the fluid inside the work chamber ( 28 ) being generated as a function of the actual value (Pos) of the position of the hydraulic actuator ( 15 ), of the target value (Pos*) of the position of the hydraulic actuator ( 15 ), and of the forecast value (P 1 ). 
   
   
     7. A method as claimed in  claim 6 , wherein a target value (Vel*) of the speed of the hydraulic actuator ( 15 ), and a target value (Acc*) of acceleration of the clutch are generated; the forecast value (P 1 ) being generated as a function of the actual value (Pos) of the position of the hydraulic actuator ( 15 ), of the target value (Vel*) of the speed of the hydraulic actuator, and of the target value (Acc*) of acceleration of the clutch. 
   
   
     8. A method as claimed in  claim 1 , wherein a target value (Vel*) of the speed of the hydraulic actuator ( 15 ) is generated, an actual value (Pt) of the pressure of the fluid in the drain tank ( 19 ) is estimated, and an actual value (Pp) of the pressure of the fluid in the storage tank ( 23 ) is measured; the control signal (I*) being calculated as a function of the actual value (Put) of the pressure of the fluid inside the work chamber ( 28 ), of the target value (Put*) of the pressure of the fluid inside the work chamber ( 28 ), of the difference between the target value (Pos*) and actual value (Pos) of the position of the hydraulic actuator ( 15 ), of the target value (Vel*) of the speed of the hydraulic actuator, of the actual value (Pt) of the pressure of the fluid in the drain tank ( 19 ), and of the actual value (Pp) of the pressure of the fluid in the storage tank ( 23 ). 
   
   
     9. A method as claimed in  claim 1 , wherein the control signal (I*) represents a target value of the current circulating in an electric actuator of the solenoid valve ( 25 ); the electric actuator of the solenoid valve ( 25 ) implementing feedback control of the current circulating through the electric actuator itself. 
   
   
     10. A control unit ( 17 ) for controlling a clutch ( 7 ) powered by a hydraulic actuator ( 15 ) comprising a work chamber ( 28 ), which is filled with a fluid and connected to a solenoid valve ( 25 ) for selective connection to a drain tank ( 19 ) for draining the fluid, or to a storage tank ( 23 ) for accumulating pressurized fluid; the control unit ( 17 ) comprising a reference generator ( 37 ) for generating a target value (Pos*) of the position of the hydraulic actuator ( 15 ), a first sensor ( 36 ) for measuring an actual value (Pos) of the position of the hydraulic actuator ( 15 ), and a controller ( 41 ) for calculating a control signal (I*) for controlling the solenoid valve ( 25 ) by feedback control of the position of the hydraulic actuator ( 15 ); and the control unit ( 17 ) being characterized by comprising a second sensor ( 35 ) for estimating an actual value (Put) of the pressure of the fluid inside the work chamber ( 28 ), and a regulator ( 40 ) for generating a target value (Put*) of the pressure of the fluid inside the work chamber ( 28 ); the controller ( 41 ) calculating the control signal (I*) using both feedback control of the position of the hydraulic actuator ( 15 ), and feedback control of the pressure of the fluid inside the work chamber ( 28 ). 
   
   
     11. A control unit ( 17 ) as claimed in  claim 10 , wherein a pipe ( 27 ) extends between the work chamber ( 28 ) and the solenoid valve ( 25 ), is connected permanently to the work chamber ( 28 ), and houses the second sensor ( 35 ) close to the work chamber ( 28 ). 
   
   
     12. A control unit ( 17 ) as claimed in  claim 11 , wherein the pipe ( 27 ) is defined by a flexible portion ( 31 ) connecting the solenoid valve ( 25 ) to a connecting block ( 32 ) integral with a housing ( 8 ) of the clutch ( 7 ), and by a rigid portion ( 33 ) connecting the connecting block ( 32 ) to the work chamber ( 28 ). 
   
   
     13. A control unit ( 17 ) as claimed in  claim 10 , wherein the regulator ( 40 ) generates the target value (Put*) of the pressure of the fluid inside the work chamber ( 28 ) as a function of the actual value (Pos) of the position of the hydraulic actuator ( 15 ), and of the target value (Pos*) of the position of the hydraulic actuator ( 15 ). 
   
   
     14. A control unit ( 17 ) as claimed in  claim 10 , and comprising a computing block ( 38 ) for calculating a forecast value (P 1 ) predicting the value of the pressure of the fluid inside the work chamber ( 28 ); the regulator ( 40 ) generating the target value (Put*) of the pressure of the fluid inside the work chamber ( 28 ) as a function of the actual value (Pos) of the position of the hydraulic actuator ( 15 ), of the target value (Pos*) of the position of the hydraulic actuator ( 15 ), and of the forecast value (P 1 ).